Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Wind turbine rotor blades typically include an outer body skin or shell formed from a composite laminate material. In general, the body shell is relatively lightweight and has structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. In addition, wind turbine blades are becoming increasingly longer in order to produce more power. As a result, the blades must be stiffer and thus heavier so as to mitigate loads on the rotor.
To increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner surfaces of the shell. The spar caps are typically constructed from laminate composites (e.g., glass fiber laminate composites and/or carbon fiber laminate composites) that include dry or non-cured fabric plies that are laid up within the blade mold and subsequently infused with resin. Such materials, however, can be difficult to control during the manufacturing process and/or are often defect prone and/or highly labor intensive due to handling of the non-cured fabrics and the challenges of infusing large laminated structures.
As such, recent attempts have been made to form spar caps from pre-fabricated, pre-cured laminate composites that can be produced in thicker sections, and are typically less susceptible to defects. However, the use of these thicker, pre-cured laminates also presents unique challenges during the blade manufacturing process. For example, the thicker pre-cured laminates present challenges with respect to conforming the individual laminate plies or plates to the desired curvature of the blade due to the stiffness of such plates.
Accordingly, a rotor blade with features that allow pre-fabricated, pre-cured laminate composite plates to be used to form the blade's spar caps without requiring such plates to conform to the chordwise curvature of the rotor blade would be welcomed in the technology.